| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Common Block IO controller cgroup interface |
| * |
| * Based on ideas and code from CFQ, CFS and BFQ: |
| * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> |
| * |
| * Copyright (C) 2008 Fabio Checconi <fabio@gandalf.sssup.it> |
| * Paolo Valente <paolo.valente@unimore.it> |
| * |
| * Copyright (C) 2009 Vivek Goyal <vgoyal@redhat.com> |
| * Nauman Rafique <nauman@google.com> |
| * |
| * For policy-specific per-blkcg data: |
| * Copyright (C) 2015 Paolo Valente <paolo.valente@unimore.it> |
| * Arianna Avanzini <avanzini.arianna@gmail.com> |
| */ |
| #include <linux/ioprio.h> |
| #include <linux/kdev_t.h> |
| #include <linux/module.h> |
| #include <linux/sched/signal.h> |
| #include <linux/err.h> |
| #include <linux/blkdev.h> |
| #include <linux/backing-dev.h> |
| #include <linux/slab.h> |
| #include <linux/genhd.h> |
| #include <linux/delay.h> |
| #include <linux/atomic.h> |
| #include <linux/ctype.h> |
| #include <linux/blk-cgroup.h> |
| #include <linux/tracehook.h> |
| #include <linux/psi.h> |
| #include "blk.h" |
| |
| #define MAX_KEY_LEN 100 |
| |
| /* |
| * blkcg_pol_mutex protects blkcg_policy[] and policy [de]activation. |
| * blkcg_pol_register_mutex nests outside of it and synchronizes entire |
| * policy [un]register operations including cgroup file additions / |
| * removals. Putting cgroup file registration outside blkcg_pol_mutex |
| * allows grabbing it from cgroup callbacks. |
| */ |
| static DEFINE_MUTEX(blkcg_pol_register_mutex); |
| static DEFINE_MUTEX(blkcg_pol_mutex); |
| |
| struct blkcg blkcg_root; |
| EXPORT_SYMBOL_GPL(blkcg_root); |
| |
| struct cgroup_subsys_state * const blkcg_root_css = &blkcg_root.css; |
| EXPORT_SYMBOL_GPL(blkcg_root_css); |
| |
| static struct blkcg_policy *blkcg_policy[BLKCG_MAX_POLS]; |
| |
| static LIST_HEAD(all_blkcgs); /* protected by blkcg_pol_mutex */ |
| |
| bool blkcg_debug_stats = false; |
| static struct workqueue_struct *blkcg_punt_bio_wq; |
| |
| static bool blkcg_policy_enabled(struct request_queue *q, |
| const struct blkcg_policy *pol) |
| { |
| return pol && test_bit(pol->plid, q->blkcg_pols); |
| } |
| |
| /** |
| * blkg_free - free a blkg |
| * @blkg: blkg to free |
| * |
| * Free @blkg which may be partially allocated. |
| */ |
| static void blkg_free(struct blkcg_gq *blkg) |
| { |
| int i; |
| |
| if (!blkg) |
| return; |
| |
| for (i = 0; i < BLKCG_MAX_POLS; i++) |
| if (blkg->pd[i]) |
| blkcg_policy[i]->pd_free_fn(blkg->pd[i]); |
| |
| free_percpu(blkg->iostat_cpu); |
| percpu_ref_exit(&blkg->refcnt); |
| kfree(blkg); |
| } |
| |
| static void __blkg_release(struct rcu_head *rcu) |
| { |
| struct blkcg_gq *blkg = container_of(rcu, struct blkcg_gq, rcu_head); |
| |
| WARN_ON(!bio_list_empty(&blkg->async_bios)); |
| |
| /* release the blkcg and parent blkg refs this blkg has been holding */ |
| css_put(&blkg->blkcg->css); |
| if (blkg->parent) |
| blkg_put(blkg->parent); |
| blkg_free(blkg); |
| } |
| |
| /* |
| * A group is RCU protected, but having an rcu lock does not mean that one |
| * can access all the fields of blkg and assume these are valid. For |
| * example, don't try to follow throtl_data and request queue links. |
| * |
| * Having a reference to blkg under an rcu allows accesses to only values |
| * local to groups like group stats and group rate limits. |
| */ |
| static void blkg_release(struct percpu_ref *ref) |
| { |
| struct blkcg_gq *blkg = container_of(ref, struct blkcg_gq, refcnt); |
| |
| call_rcu(&blkg->rcu_head, __blkg_release); |
| } |
| |
| static void blkg_async_bio_workfn(struct work_struct *work) |
| { |
| struct blkcg_gq *blkg = container_of(work, struct blkcg_gq, |
| async_bio_work); |
| struct bio_list bios = BIO_EMPTY_LIST; |
| struct bio *bio; |
| struct blk_plug plug; |
| bool need_plug = false; |
| |
| /* as long as there are pending bios, @blkg can't go away */ |
| spin_lock_bh(&blkg->async_bio_lock); |
| bio_list_merge(&bios, &blkg->async_bios); |
| bio_list_init(&blkg->async_bios); |
| spin_unlock_bh(&blkg->async_bio_lock); |
| |
| /* start plug only when bio_list contains at least 2 bios */ |
| if (bios.head && bios.head->bi_next) { |
| need_plug = true; |
| blk_start_plug(&plug); |
| } |
| while ((bio = bio_list_pop(&bios))) |
| submit_bio(bio); |
| if (need_plug) |
| blk_finish_plug(&plug); |
| } |
| |
| /** |
| * blkg_alloc - allocate a blkg |
| * @blkcg: block cgroup the new blkg is associated with |
| * @q: request_queue the new blkg is associated with |
| * @gfp_mask: allocation mask to use |
| * |
| * Allocate a new blkg assocating @blkcg and @q. |
| */ |
| static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, |
| gfp_t gfp_mask) |
| { |
| struct blkcg_gq *blkg; |
| int i, cpu; |
| |
| /* alloc and init base part */ |
| blkg = kzalloc_node(sizeof(*blkg), gfp_mask, q->node); |
| if (!blkg) |
| return NULL; |
| |
| if (percpu_ref_init(&blkg->refcnt, blkg_release, 0, gfp_mask)) |
| goto err_free; |
| |
| blkg->iostat_cpu = alloc_percpu_gfp(struct blkg_iostat_set, gfp_mask); |
| if (!blkg->iostat_cpu) |
| goto err_free; |
| |
| blkg->q = q; |
| INIT_LIST_HEAD(&blkg->q_node); |
| spin_lock_init(&blkg->async_bio_lock); |
| bio_list_init(&blkg->async_bios); |
| INIT_WORK(&blkg->async_bio_work, blkg_async_bio_workfn); |
| blkg->blkcg = blkcg; |
| |
| u64_stats_init(&blkg->iostat.sync); |
| for_each_possible_cpu(cpu) |
| u64_stats_init(&per_cpu_ptr(blkg->iostat_cpu, cpu)->sync); |
| |
| for (i = 0; i < BLKCG_MAX_POLS; i++) { |
| struct blkcg_policy *pol = blkcg_policy[i]; |
| struct blkg_policy_data *pd; |
| |
| if (!blkcg_policy_enabled(q, pol)) |
| continue; |
| |
| /* alloc per-policy data and attach it to blkg */ |
| pd = pol->pd_alloc_fn(gfp_mask, q, blkcg); |
| if (!pd) |
| goto err_free; |
| |
| blkg->pd[i] = pd; |
| pd->blkg = blkg; |
| pd->plid = i; |
| } |
| |
| return blkg; |
| |
| err_free: |
| blkg_free(blkg); |
| return NULL; |
| } |
| |
| struct blkcg_gq *blkg_lookup_slowpath(struct blkcg *blkcg, |
| struct request_queue *q, bool update_hint) |
| { |
| struct blkcg_gq *blkg; |
| |
| /* |
| * Hint didn't match. Look up from the radix tree. Note that the |
| * hint can only be updated under queue_lock as otherwise @blkg |
| * could have already been removed from blkg_tree. The caller is |
| * responsible for grabbing queue_lock if @update_hint. |
| */ |
| blkg = radix_tree_lookup(&blkcg->blkg_tree, q->id); |
| if (blkg && blkg->q == q) { |
| if (update_hint) { |
| lockdep_assert_held(&q->queue_lock); |
| rcu_assign_pointer(blkcg->blkg_hint, blkg); |
| } |
| return blkg; |
| } |
| |
| return NULL; |
| } |
| EXPORT_SYMBOL_GPL(blkg_lookup_slowpath); |
| |
| /* |
| * If @new_blkg is %NULL, this function tries to allocate a new one as |
| * necessary using %GFP_NOWAIT. @new_blkg is always consumed on return. |
| */ |
| static struct blkcg_gq *blkg_create(struct blkcg *blkcg, |
| struct request_queue *q, |
| struct blkcg_gq *new_blkg) |
| { |
| struct blkcg_gq *blkg; |
| int i, ret; |
| |
| WARN_ON_ONCE(!rcu_read_lock_held()); |
| lockdep_assert_held(&q->queue_lock); |
| |
| /* request_queue is dying, do not create/recreate a blkg */ |
| if (blk_queue_dying(q)) { |
| ret = -ENODEV; |
| goto err_free_blkg; |
| } |
| |
| /* blkg holds a reference to blkcg */ |
| if (!css_tryget_online(&blkcg->css)) { |
| ret = -ENODEV; |
| goto err_free_blkg; |
| } |
| |
| /* allocate */ |
| if (!new_blkg) { |
| new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT | __GFP_NOWARN); |
| if (unlikely(!new_blkg)) { |
| ret = -ENOMEM; |
| goto err_put_css; |
| } |
| } |
| blkg = new_blkg; |
| |
| /* link parent */ |
| if (blkcg_parent(blkcg)) { |
| blkg->parent = __blkg_lookup(blkcg_parent(blkcg), q, false); |
| if (WARN_ON_ONCE(!blkg->parent)) { |
| ret = -ENODEV; |
| goto err_put_css; |
| } |
| blkg_get(blkg->parent); |
| } |
| |
| /* invoke per-policy init */ |
| for (i = 0; i < BLKCG_MAX_POLS; i++) { |
| struct blkcg_policy *pol = blkcg_policy[i]; |
| |
| if (blkg->pd[i] && pol->pd_init_fn) |
| pol->pd_init_fn(blkg->pd[i]); |
| } |
| |
| /* insert */ |
| spin_lock(&blkcg->lock); |
| ret = radix_tree_insert(&blkcg->blkg_tree, q->id, blkg); |
| if (likely(!ret)) { |
| hlist_add_head_rcu(&blkg->blkcg_node, &blkcg->blkg_list); |
| list_add(&blkg->q_node, &q->blkg_list); |
| |
| for (i = 0; i < BLKCG_MAX_POLS; i++) { |
| struct blkcg_policy *pol = blkcg_policy[i]; |
| |
| if (blkg->pd[i] && pol->pd_online_fn) |
| pol->pd_online_fn(blkg->pd[i]); |
| } |
| } |
| blkg->online = true; |
| spin_unlock(&blkcg->lock); |
| |
| if (!ret) |
| return blkg; |
| |
| /* @blkg failed fully initialized, use the usual release path */ |
| blkg_put(blkg); |
| return ERR_PTR(ret); |
| |
| err_put_css: |
| css_put(&blkcg->css); |
| err_free_blkg: |
| blkg_free(new_blkg); |
| return ERR_PTR(ret); |
| } |
| |
| /** |
| * blkg_lookup_create - lookup blkg, try to create one if not there |
| * @blkcg: blkcg of interest |
| * @q: request_queue of interest |
| * |
| * Lookup blkg for the @blkcg - @q pair. If it doesn't exist, try to |
| * create one. blkg creation is performed recursively from blkcg_root such |
| * that all non-root blkg's have access to the parent blkg. This function |
| * should be called under RCU read lock and takes @q->queue_lock. |
| * |
| * Returns the blkg or the closest blkg if blkg_create() fails as it walks |
| * down from root. |
| */ |
| static struct blkcg_gq *blkg_lookup_create(struct blkcg *blkcg, |
| struct request_queue *q) |
| { |
| struct blkcg_gq *blkg; |
| unsigned long flags; |
| |
| WARN_ON_ONCE(!rcu_read_lock_held()); |
| |
| blkg = blkg_lookup(blkcg, q); |
| if (blkg) |
| return blkg; |
| |
| spin_lock_irqsave(&q->queue_lock, flags); |
| blkg = __blkg_lookup(blkcg, q, true); |
| if (blkg) |
| goto found; |
| |
| /* |
| * Create blkgs walking down from blkcg_root to @blkcg, so that all |
| * non-root blkgs have access to their parents. Returns the closest |
| * blkg to the intended blkg should blkg_create() fail. |
| */ |
| while (true) { |
| struct blkcg *pos = blkcg; |
| struct blkcg *parent = blkcg_parent(blkcg); |
| struct blkcg_gq *ret_blkg = q->root_blkg; |
| |
| while (parent) { |
| blkg = __blkg_lookup(parent, q, false); |
| if (blkg) { |
| /* remember closest blkg */ |
| ret_blkg = blkg; |
| break; |
| } |
| pos = parent; |
| parent = blkcg_parent(parent); |
| } |
| |
| blkg = blkg_create(pos, q, NULL); |
| if (IS_ERR(blkg)) { |
| blkg = ret_blkg; |
| break; |
| } |
| if (pos == blkcg) |
| break; |
| } |
| |
| found: |
| spin_unlock_irqrestore(&q->queue_lock, flags); |
| return blkg; |
| } |
| |
| static void blkg_destroy(struct blkcg_gq *blkg) |
| { |
| struct blkcg *blkcg = blkg->blkcg; |
| int i; |
| |
| lockdep_assert_held(&blkg->q->queue_lock); |
| lockdep_assert_held(&blkcg->lock); |
| |
| /* Something wrong if we are trying to remove same group twice */ |
| WARN_ON_ONCE(list_empty(&blkg->q_node)); |
| WARN_ON_ONCE(hlist_unhashed(&blkg->blkcg_node)); |
| |
| for (i = 0; i < BLKCG_MAX_POLS; i++) { |
| struct blkcg_policy *pol = blkcg_policy[i]; |
| |
| if (blkg->pd[i] && pol->pd_offline_fn) |
| pol->pd_offline_fn(blkg->pd[i]); |
| } |
| |
| blkg->online = false; |
| |
| radix_tree_delete(&blkcg->blkg_tree, blkg->q->id); |
| list_del_init(&blkg->q_node); |
| hlist_del_init_rcu(&blkg->blkcg_node); |
| |
| /* |
| * Both setting lookup hint to and clearing it from @blkg are done |
| * under queue_lock. If it's not pointing to @blkg now, it never |
| * will. Hint assignment itself can race safely. |
| */ |
| if (rcu_access_pointer(blkcg->blkg_hint) == blkg) |
| rcu_assign_pointer(blkcg->blkg_hint, NULL); |
| |
| /* |
| * Put the reference taken at the time of creation so that when all |
| * queues are gone, group can be destroyed. |
| */ |
| percpu_ref_kill(&blkg->refcnt); |
| } |
| |
| /** |
| * blkg_destroy_all - destroy all blkgs associated with a request_queue |
| * @q: request_queue of interest |
| * |
| * Destroy all blkgs associated with @q. |
| */ |
| static void blkg_destroy_all(struct request_queue *q) |
| { |
| struct blkcg_gq *blkg, *n; |
| |
| spin_lock_irq(&q->queue_lock); |
| list_for_each_entry_safe(blkg, n, &q->blkg_list, q_node) { |
| struct blkcg *blkcg = blkg->blkcg; |
| |
| spin_lock(&blkcg->lock); |
| blkg_destroy(blkg); |
| spin_unlock(&blkcg->lock); |
| } |
| |
| q->root_blkg = NULL; |
| spin_unlock_irq(&q->queue_lock); |
| } |
| |
| static int blkcg_reset_stats(struct cgroup_subsys_state *css, |
| struct cftype *cftype, u64 val) |
| { |
| struct blkcg *blkcg = css_to_blkcg(css); |
| struct blkcg_gq *blkg; |
| int i, cpu; |
| |
| mutex_lock(&blkcg_pol_mutex); |
| spin_lock_irq(&blkcg->lock); |
| |
| /* |
| * Note that stat reset is racy - it doesn't synchronize against |
| * stat updates. This is a debug feature which shouldn't exist |
| * anyway. If you get hit by a race, retry. |
| */ |
| hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { |
| for_each_possible_cpu(cpu) { |
| struct blkg_iostat_set *bis = |
| per_cpu_ptr(blkg->iostat_cpu, cpu); |
| memset(bis, 0, sizeof(*bis)); |
| } |
| memset(&blkg->iostat, 0, sizeof(blkg->iostat)); |
| |
| for (i = 0; i < BLKCG_MAX_POLS; i++) { |
| struct blkcg_policy *pol = blkcg_policy[i]; |
| |
| if (blkg->pd[i] && pol->pd_reset_stats_fn) |
| pol->pd_reset_stats_fn(blkg->pd[i]); |
| } |
| } |
| |
| spin_unlock_irq(&blkcg->lock); |
| mutex_unlock(&blkcg_pol_mutex); |
| return 0; |
| } |
| |
| const char *blkg_dev_name(struct blkcg_gq *blkg) |
| { |
| /* some drivers (floppy) instantiate a queue w/o disk registered */ |
| if (blkg->q->backing_dev_info->dev) |
| return bdi_dev_name(blkg->q->backing_dev_info); |
| return NULL; |
| } |
| |
| /** |
| * blkcg_print_blkgs - helper for printing per-blkg data |
| * @sf: seq_file to print to |
| * @blkcg: blkcg of interest |
| * @prfill: fill function to print out a blkg |
| * @pol: policy in question |
| * @data: data to be passed to @prfill |
| * @show_total: to print out sum of prfill return values or not |
| * |
| * This function invokes @prfill on each blkg of @blkcg if pd for the |
| * policy specified by @pol exists. @prfill is invoked with @sf, the |
| * policy data and @data and the matching queue lock held. If @show_total |
| * is %true, the sum of the return values from @prfill is printed with |
| * "Total" label at the end. |
| * |
| * This is to be used to construct print functions for |
| * cftype->read_seq_string method. |
| */ |
| void blkcg_print_blkgs(struct seq_file *sf, struct blkcg *blkcg, |
| u64 (*prfill)(struct seq_file *, |
| struct blkg_policy_data *, int), |
| const struct blkcg_policy *pol, int data, |
| bool show_total) |
| { |
| struct blkcg_gq *blkg; |
| u64 total = 0; |
| |
| rcu_read_lock(); |
| hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { |
| spin_lock_irq(&blkg->q->queue_lock); |
| if (blkcg_policy_enabled(blkg->q, pol)) |
| total += prfill(sf, blkg->pd[pol->plid], data); |
| spin_unlock_irq(&blkg->q->queue_lock); |
| } |
| rcu_read_unlock(); |
| |
| if (show_total) |
| seq_printf(sf, "Total %llu\n", (unsigned long long)total); |
| } |
| EXPORT_SYMBOL_GPL(blkcg_print_blkgs); |
| |
| /** |
| * __blkg_prfill_u64 - prfill helper for a single u64 value |
| * @sf: seq_file to print to |
| * @pd: policy private data of interest |
| * @v: value to print |
| * |
| * Print @v to @sf for the device assocaited with @pd. |
| */ |
| u64 __blkg_prfill_u64(struct seq_file *sf, struct blkg_policy_data *pd, u64 v) |
| { |
| const char *dname = blkg_dev_name(pd->blkg); |
| |
| if (!dname) |
| return 0; |
| |
| seq_printf(sf, "%s %llu\n", dname, (unsigned long long)v); |
| return v; |
| } |
| EXPORT_SYMBOL_GPL(__blkg_prfill_u64); |
| |
| /* Performs queue bypass and policy enabled checks then looks up blkg. */ |
| static struct blkcg_gq *blkg_lookup_check(struct blkcg *blkcg, |
| const struct blkcg_policy *pol, |
| struct request_queue *q) |
| { |
| WARN_ON_ONCE(!rcu_read_lock_held()); |
| lockdep_assert_held(&q->queue_lock); |
| |
| if (!blkcg_policy_enabled(q, pol)) |
| return ERR_PTR(-EOPNOTSUPP); |
| return __blkg_lookup(blkcg, q, true /* update_hint */); |
| } |
| |
| /** |
| * blkcg_conf_open_bdev - parse and open bdev for per-blkg config update |
| * @inputp: input string pointer |
| * |
| * Parse the device node prefix part, MAJ:MIN, of per-blkg config update |
| * from @input and get and return the matching bdev. *@inputp is |
| * updated to point past the device node prefix. Returns an ERR_PTR() |
| * value on error. |
| * |
| * Use this function iff blkg_conf_prep() can't be used for some reason. |
| */ |
| struct block_device *blkcg_conf_open_bdev(char **inputp) |
| { |
| char *input = *inputp; |
| unsigned int major, minor; |
| struct block_device *bdev; |
| int key_len; |
| |
| if (sscanf(input, "%u:%u%n", &major, &minor, &key_len) != 2) |
| return ERR_PTR(-EINVAL); |
| |
| input += key_len; |
| if (!isspace(*input)) |
| return ERR_PTR(-EINVAL); |
| input = skip_spaces(input); |
| |
| bdev = blkdev_get_no_open(MKDEV(major, minor)); |
| if (!bdev) |
| return ERR_PTR(-ENODEV); |
| if (bdev_is_partition(bdev)) { |
| blkdev_put_no_open(bdev); |
| return ERR_PTR(-ENODEV); |
| } |
| |
| *inputp = input; |
| return bdev; |
| } |
| |
| /** |
| * blkg_conf_prep - parse and prepare for per-blkg config update |
| * @blkcg: target block cgroup |
| * @pol: target policy |
| * @input: input string |
| * @ctx: blkg_conf_ctx to be filled |
| * |
| * Parse per-blkg config update from @input and initialize @ctx with the |
| * result. @ctx->blkg points to the blkg to be updated and @ctx->body the |
| * part of @input following MAJ:MIN. This function returns with RCU read |
| * lock and queue lock held and must be paired with blkg_conf_finish(). |
| */ |
| int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol, |
| char *input, struct blkg_conf_ctx *ctx) |
| __acquires(rcu) __acquires(&bdev->bd_disk->queue->queue_lock) |
| { |
| struct block_device *bdev; |
| struct request_queue *q; |
| struct blkcg_gq *blkg; |
| int ret; |
| |
| bdev = blkcg_conf_open_bdev(&input); |
| if (IS_ERR(bdev)) |
| return PTR_ERR(bdev); |
| |
| q = bdev->bd_disk->queue; |
| |
| rcu_read_lock(); |
| spin_lock_irq(&q->queue_lock); |
| |
| blkg = blkg_lookup_check(blkcg, pol, q); |
| if (IS_ERR(blkg)) { |
| ret = PTR_ERR(blkg); |
| goto fail_unlock; |
| } |
| |
| if (blkg) |
| goto success; |
| |
| /* |
| * Create blkgs walking down from blkcg_root to @blkcg, so that all |
| * non-root blkgs have access to their parents. |
| */ |
| while (true) { |
| struct blkcg *pos = blkcg; |
| struct blkcg *parent; |
| struct blkcg_gq *new_blkg; |
| |
| parent = blkcg_parent(blkcg); |
| while (parent && !__blkg_lookup(parent, q, false)) { |
| pos = parent; |
| parent = blkcg_parent(parent); |
| } |
| |
| /* Drop locks to do new blkg allocation with GFP_KERNEL. */ |
| spin_unlock_irq(&q->queue_lock); |
| rcu_read_unlock(); |
| |
| new_blkg = blkg_alloc(pos, q, GFP_KERNEL); |
| if (unlikely(!new_blkg)) { |
| ret = -ENOMEM; |
| goto fail; |
| } |
| |
| if (radix_tree_preload(GFP_KERNEL)) { |
| blkg_free(new_blkg); |
| ret = -ENOMEM; |
| goto fail; |
| } |
| |
| rcu_read_lock(); |
| spin_lock_irq(&q->queue_lock); |
| |
| blkg = blkg_lookup_check(pos, pol, q); |
| if (IS_ERR(blkg)) { |
| ret = PTR_ERR(blkg); |
| blkg_free(new_blkg); |
| goto fail_preloaded; |
| } |
| |
| if (blkg) { |
| blkg_free(new_blkg); |
| } else { |
| blkg = blkg_create(pos, q, new_blkg); |
| if (IS_ERR(blkg)) { |
| ret = PTR_ERR(blkg); |
| goto fail_preloaded; |
| } |
| } |
| |
| radix_tree_preload_end(); |
| |
| if (pos == blkcg) |
| goto success; |
| } |
| success: |
| ctx->bdev = bdev; |
| ctx->blkg = blkg; |
| ctx->body = input; |
| return 0; |
| |
| fail_preloaded: |
| radix_tree_preload_end(); |
| fail_unlock: |
| spin_unlock_irq(&q->queue_lock); |
| rcu_read_unlock(); |
| fail: |
| blkdev_put_no_open(bdev); |
| /* |
| * If queue was bypassing, we should retry. Do so after a |
| * short msleep(). It isn't strictly necessary but queue |
| * can be bypassing for some time and it's always nice to |
| * avoid busy looping. |
| */ |
| if (ret == -EBUSY) { |
| msleep(10); |
| ret = restart_syscall(); |
| } |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(blkg_conf_prep); |
| |
| /** |
| * blkg_conf_finish - finish up per-blkg config update |
| * @ctx: blkg_conf_ctx intiailized by blkg_conf_prep() |
| * |
| * Finish up after per-blkg config update. This function must be paired |
| * with blkg_conf_prep(). |
| */ |
| void blkg_conf_finish(struct blkg_conf_ctx *ctx) |
| __releases(&ctx->bdev->bd_disk->queue->queue_lock) __releases(rcu) |
| { |
| spin_unlock_irq(&ctx->bdev->bd_disk->queue->queue_lock); |
| rcu_read_unlock(); |
| blkdev_put_no_open(ctx->bdev); |
| } |
| EXPORT_SYMBOL_GPL(blkg_conf_finish); |
| |
| static void blkg_iostat_set(struct blkg_iostat *dst, struct blkg_iostat *src) |
| { |
| int i; |
| |
| for (i = 0; i < BLKG_IOSTAT_NR; i++) { |
| dst->bytes[i] = src->bytes[i]; |
| dst->ios[i] = src->ios[i]; |
| } |
| } |
| |
| static void blkg_iostat_add(struct blkg_iostat *dst, struct blkg_iostat *src) |
| { |
| int i; |
| |
| for (i = 0; i < BLKG_IOSTAT_NR; i++) { |
| dst->bytes[i] += src->bytes[i]; |
| dst->ios[i] += src->ios[i]; |
| } |
| } |
| |
| static void blkg_iostat_sub(struct blkg_iostat *dst, struct blkg_iostat *src) |
| { |
| int i; |
| |
| for (i = 0; i < BLKG_IOSTAT_NR; i++) { |
| dst->bytes[i] -= src->bytes[i]; |
| dst->ios[i] -= src->ios[i]; |
| } |
| } |
| |
| static void blkcg_rstat_flush(struct cgroup_subsys_state *css, int cpu) |
| { |
| struct blkcg *blkcg = css_to_blkcg(css); |
| struct blkcg_gq *blkg; |
| |
| rcu_read_lock(); |
| |
| hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { |
| struct blkcg_gq *parent = blkg->parent; |
| struct blkg_iostat_set *bisc = per_cpu_ptr(blkg->iostat_cpu, cpu); |
| struct blkg_iostat cur, delta; |
| unsigned int seq; |
| |
| /* fetch the current per-cpu values */ |
| do { |
| seq = u64_stats_fetch_begin(&bisc->sync); |
| blkg_iostat_set(&cur, &bisc->cur); |
| } while (u64_stats_fetch_retry(&bisc->sync, seq)); |
| |
| /* propagate percpu delta to global */ |
| u64_stats_update_begin(&blkg->iostat.sync); |
| blkg_iostat_set(&delta, &cur); |
| blkg_iostat_sub(&delta, &bisc->last); |
| blkg_iostat_add(&blkg->iostat.cur, &delta); |
| blkg_iostat_add(&bisc->last, &delta); |
| u64_stats_update_end(&blkg->iostat.sync); |
| |
| /* propagate global delta to parent */ |
| if (parent) { |
| u64_stats_update_begin(&parent->iostat.sync); |
| blkg_iostat_set(&delta, &blkg->iostat.cur); |
| blkg_iostat_sub(&delta, &blkg->iostat.last); |
| blkg_iostat_add(&parent->iostat.cur, &delta); |
| blkg_iostat_add(&blkg->iostat.last, &delta); |
| u64_stats_update_end(&parent->iostat.sync); |
| } |
| } |
| |
| rcu_read_unlock(); |
| } |
| |
| /* |
| * The rstat algorithms intentionally don't handle the root cgroup to avoid |
| * incurring overhead when no cgroups are defined. For that reason, |
| * cgroup_rstat_flush in blkcg_print_stat does not actually fill out the |
| * iostat in the root cgroup's blkcg_gq. |
| * |
| * However, we would like to re-use the printing code between the root and |
| * non-root cgroups to the extent possible. For that reason, we simulate |
| * flushing the root cgroup's stats by explicitly filling in the iostat |
| * with disk level statistics. |
| */ |
| static void blkcg_fill_root_iostats(void) |
| { |
| struct class_dev_iter iter; |
| struct device *dev; |
| |
| class_dev_iter_init(&iter, &block_class, NULL, &disk_type); |
| while ((dev = class_dev_iter_next(&iter))) { |
| struct block_device *bdev = dev_to_bdev(dev); |
| struct blkcg_gq *blkg = |
| blk_queue_root_blkg(bdev->bd_disk->queue); |
| struct blkg_iostat tmp; |
| int cpu; |
| |
| memset(&tmp, 0, sizeof(tmp)); |
| for_each_possible_cpu(cpu) { |
| struct disk_stats *cpu_dkstats; |
| |
| cpu_dkstats = per_cpu_ptr(bdev->bd_stats, cpu); |
| tmp.ios[BLKG_IOSTAT_READ] += |
| cpu_dkstats->ios[STAT_READ]; |
| tmp.ios[BLKG_IOSTAT_WRITE] += |
| cpu_dkstats->ios[STAT_WRITE]; |
| tmp.ios[BLKG_IOSTAT_DISCARD] += |
| cpu_dkstats->ios[STAT_DISCARD]; |
| // convert sectors to bytes |
| tmp.bytes[BLKG_IOSTAT_READ] += |
| cpu_dkstats->sectors[STAT_READ] << 9; |
| tmp.bytes[BLKG_IOSTAT_WRITE] += |
| cpu_dkstats->sectors[STAT_WRITE] << 9; |
| tmp.bytes[BLKG_IOSTAT_DISCARD] += |
| cpu_dkstats->sectors[STAT_DISCARD] << 9; |
| |
| u64_stats_update_begin(&blkg->iostat.sync); |
| blkg_iostat_set(&blkg->iostat.cur, &tmp); |
| u64_stats_update_end(&blkg->iostat.sync); |
| } |
| } |
| } |
| |
| static int blkcg_print_stat(struct seq_file *sf, void *v) |
| { |
| struct blkcg *blkcg = css_to_blkcg(seq_css(sf)); |
| struct blkcg_gq *blkg; |
| |
| if (!seq_css(sf)->parent) |
| blkcg_fill_root_iostats(); |
| else |
| cgroup_rstat_flush(blkcg->css.cgroup); |
| |
| rcu_read_lock(); |
| |
| hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { |
| struct blkg_iostat_set *bis = &blkg->iostat; |
| const char *dname; |
| char *buf; |
| u64 rbytes, wbytes, rios, wios, dbytes, dios; |
| size_t size = seq_get_buf(sf, &buf), off = 0; |
| int i; |
| bool has_stats = false; |
| unsigned seq; |
| |
| spin_lock_irq(&blkg->q->queue_lock); |
| |
| if (!blkg->online) |
| goto skip; |
| |
| dname = blkg_dev_name(blkg); |
| if (!dname) |
| goto skip; |
| |
| /* |
| * Hooray string manipulation, count is the size written NOT |
| * INCLUDING THE \0, so size is now count+1 less than what we |
| * had before, but we want to start writing the next bit from |
| * the \0 so we only add count to buf. |
| */ |
| off += scnprintf(buf+off, size-off, "%s ", dname); |
| |
| do { |
| seq = u64_stats_fetch_begin(&bis->sync); |
| |
| rbytes = bis->cur.bytes[BLKG_IOSTAT_READ]; |
| wbytes = bis->cur.bytes[BLKG_IOSTAT_WRITE]; |
| dbytes = bis->cur.bytes[BLKG_IOSTAT_DISCARD]; |
| rios = bis->cur.ios[BLKG_IOSTAT_READ]; |
| wios = bis->cur.ios[BLKG_IOSTAT_WRITE]; |
| dios = bis->cur.ios[BLKG_IOSTAT_DISCARD]; |
| } while (u64_stats_fetch_retry(&bis->sync, seq)); |
| |
| if (rbytes || wbytes || rios || wios) { |
| has_stats = true; |
| off += scnprintf(buf+off, size-off, |
| "rbytes=%llu wbytes=%llu rios=%llu wios=%llu dbytes=%llu dios=%llu", |
| rbytes, wbytes, rios, wios, |
| dbytes, dios); |
| } |
| |
| if (blkcg_debug_stats && atomic_read(&blkg->use_delay)) { |
| has_stats = true; |
| off += scnprintf(buf+off, size-off, |
| " use_delay=%d delay_nsec=%llu", |
| atomic_read(&blkg->use_delay), |
| (unsigned long long)atomic64_read(&blkg->delay_nsec)); |
| } |
| |
| for (i = 0; i < BLKCG_MAX_POLS; i++) { |
| struct blkcg_policy *pol = blkcg_policy[i]; |
| size_t written; |
| |
| if (!blkg->pd[i] || !pol->pd_stat_fn) |
| continue; |
| |
| written = pol->pd_stat_fn(blkg->pd[i], buf+off, size-off); |
| if (written) |
| has_stats = true; |
| off += written; |
| } |
| |
| if (has_stats) { |
| if (off < size - 1) { |
| off += scnprintf(buf+off, size-off, "\n"); |
| seq_commit(sf, off); |
| } else { |
| seq_commit(sf, -1); |
| } |
| } |
| skip: |
| spin_unlock_irq(&blkg->q->queue_lock); |
| } |
| |
| rcu_read_unlock(); |
| return 0; |
| } |
| |
| static struct cftype blkcg_files[] = { |
| { |
| .name = "stat", |
| .seq_show = blkcg_print_stat, |
| }, |
| { } /* terminate */ |
| }; |
| |
| static struct cftype blkcg_legacy_files[] = { |
| { |
| .name = "reset_stats", |
| .write_u64 = blkcg_reset_stats, |
| }, |
| { } /* terminate */ |
| }; |
| |
| /* |
| * blkcg destruction is a three-stage process. |
| * |
| * 1. Destruction starts. The blkcg_css_offline() callback is invoked |
| * which offlines writeback. Here we tie the next stage of blkg destruction |
| * to the completion of writeback associated with the blkcg. This lets us |
| * avoid punting potentially large amounts of outstanding writeback to root |
| * while maintaining any ongoing policies. The next stage is triggered when |
| * the nr_cgwbs count goes to zero. |
| * |
| * 2. When the nr_cgwbs count goes to zero, blkcg_destroy_blkgs() is called |
| * and handles the destruction of blkgs. Here the css reference held by |
| * the blkg is put back eventually allowing blkcg_css_free() to be called. |
| * This work may occur in cgwb_release_workfn() on the cgwb_release |
| * workqueue. Any submitted ios that fail to get the blkg ref will be |
| * punted to the root_blkg. |
| * |
| * 3. Once the blkcg ref count goes to zero, blkcg_css_free() is called. |
| * This finally frees the blkcg. |
| */ |
| |
| /** |
| * blkcg_css_offline - cgroup css_offline callback |
| * @css: css of interest |
| * |
| * This function is called when @css is about to go away. Here the cgwbs are |
| * offlined first and only once writeback associated with the blkcg has |
| * finished do we start step 2 (see above). |
| */ |
| static void blkcg_css_offline(struct cgroup_subsys_state *css) |
| { |
| struct blkcg *blkcg = css_to_blkcg(css); |
| |
| /* this prevents anyone from attaching or migrating to this blkcg */ |
| wb_blkcg_offline(blkcg); |
| |
| /* put the base online pin allowing step 2 to be triggered */ |
| blkcg_unpin_online(blkcg); |
| } |
| |
| /** |
| * blkcg_destroy_blkgs - responsible for shooting down blkgs |
| * @blkcg: blkcg of interest |
| * |
| * blkgs should be removed while holding both q and blkcg locks. As blkcg lock |
| * is nested inside q lock, this function performs reverse double lock dancing. |
| * Destroying the blkgs releases the reference held on the blkcg's css allowing |
| * blkcg_css_free to eventually be called. |
| * |
| * This is the blkcg counterpart of ioc_release_fn(). |
| */ |
| void blkcg_destroy_blkgs(struct blkcg *blkcg) |
| { |
| might_sleep(); |
| |
| spin_lock_irq(&blkcg->lock); |
| |
| while (!hlist_empty(&blkcg->blkg_list)) { |
| struct blkcg_gq *blkg = hlist_entry(blkcg->blkg_list.first, |
| struct blkcg_gq, blkcg_node); |
| struct request_queue *q = blkg->q; |
| |
| if (need_resched() || !spin_trylock(&q->queue_lock)) { |
| /* |
| * Given that the system can accumulate a huge number |
| * of blkgs in pathological cases, check to see if we |
| * need to rescheduling to avoid softlockup. |
| */ |
| spin_unlock_irq(&blkcg->lock); |
| cond_resched(); |
| spin_lock_irq(&blkcg->lock); |
| continue; |
| } |
| |
| blkg_destroy(blkg); |
| spin_unlock(&q->queue_lock); |
| } |
| |
| spin_unlock_irq(&blkcg->lock); |
| } |
| |
| static void blkcg_css_free(struct cgroup_subsys_state *css) |
| { |
| struct blkcg *blkcg = css_to_blkcg(css); |
| int i; |
| |
| mutex_lock(&blkcg_pol_mutex); |
| |
| list_del(&blkcg->all_blkcgs_node); |
| |
| for (i = 0; i < BLKCG_MAX_POLS; i++) |
| if (blkcg->cpd[i]) |
| blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); |
| |
| mutex_unlock(&blkcg_pol_mutex); |
| |
| kfree(blkcg); |
| } |
| |
| static struct cgroup_subsys_state * |
| blkcg_css_alloc(struct cgroup_subsys_state *parent_css) |
| { |
| struct blkcg *blkcg; |
| struct cgroup_subsys_state *ret; |
| int i; |
| |
| mutex_lock(&blkcg_pol_mutex); |
| |
| if (!parent_css) { |
| blkcg = &blkcg_root; |
| } else { |
| blkcg = kzalloc(sizeof(*blkcg), GFP_KERNEL); |
| if (!blkcg) { |
| ret = ERR_PTR(-ENOMEM); |
| goto unlock; |
| } |
| } |
| |
| for (i = 0; i < BLKCG_MAX_POLS ; i++) { |
| struct blkcg_policy *pol = blkcg_policy[i]; |
| struct blkcg_policy_data *cpd; |
| |
| /* |
| * If the policy hasn't been attached yet, wait for it |
| * to be attached before doing anything else. Otherwise, |
| * check if the policy requires any specific per-cgroup |
| * data: if it does, allocate and initialize it. |
| */ |
| if (!pol || !pol->cpd_alloc_fn) |
| continue; |
| |
| cpd = pol->cpd_alloc_fn(GFP_KERNEL); |
| if (!cpd) { |
| ret = ERR_PTR(-ENOMEM); |
| goto free_pd_blkcg; |
| } |
| blkcg->cpd[i] = cpd; |
| cpd->blkcg = blkcg; |
| cpd->plid = i; |
| if (pol->cpd_init_fn) |
| pol->cpd_init_fn(cpd); |
| } |
| |
| spin_lock_init(&blkcg->lock); |
| refcount_set(&blkcg->online_pin, 1); |
| INIT_RADIX_TREE(&blkcg->blkg_tree, GFP_NOWAIT | __GFP_NOWARN); |
| INIT_HLIST_HEAD(&blkcg->blkg_list); |
| #ifdef CONFIG_CGROUP_WRITEBACK |
| INIT_LIST_HEAD(&blkcg->cgwb_list); |
| #endif |
| list_add_tail(&blkcg->all_blkcgs_node, &all_blkcgs); |
| |
| mutex_unlock(&blkcg_pol_mutex); |
| return &blkcg->css; |
| |
| free_pd_blkcg: |
| for (i--; i >= 0; i--) |
| if (blkcg->cpd[i]) |
| blkcg_policy[i]->cpd_free_fn(blkcg->cpd[i]); |
| |
| if (blkcg != &blkcg_root) |
| kfree(blkcg); |
| unlock: |
| mutex_unlock(&blkcg_pol_mutex); |
| return ret; |
| } |
| |
| static int blkcg_css_online(struct cgroup_subsys_state *css) |
| { |
| struct blkcg *blkcg = css_to_blkcg(css); |
| struct blkcg *parent = blkcg_parent(blkcg); |
| |
| /* |
| * blkcg_pin_online() is used to delay blkcg offline so that blkgs |
| * don't go offline while cgwbs are still active on them. Pin the |
| * parent so that offline always happens towards the root. |
| */ |
| if (parent) |
| blkcg_pin_online(parent); |
| return 0; |
| } |
| |
| /** |
| * blkcg_init_queue - initialize blkcg part of request queue |
| * @q: request_queue to initialize |
| * |
| * Called from blk_alloc_queue(). Responsible for initializing blkcg |
| * part of new request_queue @q. |
| * |
| * RETURNS: |
| * 0 on success, -errno on failure. |
| */ |
| int blkcg_init_queue(struct request_queue *q) |
| { |
| struct blkcg_gq *new_blkg, *blkg; |
| bool preloaded; |
| int ret; |
| |
| new_blkg = blkg_alloc(&blkcg_root, q, GFP_KERNEL); |
| if (!new_blkg) |
| return -ENOMEM; |
| |
| preloaded = !radix_tree_preload(GFP_KERNEL); |
| |
| /* Make sure the root blkg exists. */ |
| rcu_read_lock(); |
| spin_lock_irq(&q->queue_lock); |
| blkg = blkg_create(&blkcg_root, q, new_blkg); |
| if (IS_ERR(blkg)) |
| goto err_unlock; |
| q->root_blkg = blkg; |
| spin_unlock_irq(&q->queue_lock); |
| rcu_read_unlock(); |
| |
| if (preloaded) |
| radix_tree_preload_end(); |
| |
| ret = blk_throtl_init(q); |
| if (ret) |
| goto err_destroy_all; |
| |
| ret = blk_iolatency_init(q); |
| if (ret) { |
| blk_throtl_exit(q); |
| goto err_destroy_all; |
| } |
| return 0; |
| |
| err_destroy_all: |
| blkg_destroy_all(q); |
| return ret; |
| err_unlock: |
| spin_unlock_irq(&q->queue_lock); |
| rcu_read_unlock(); |
| if (preloaded) |
| radix_tree_preload_end(); |
| return PTR_ERR(blkg); |
| } |
| |
| /** |
| * blkcg_exit_queue - exit and release blkcg part of request_queue |
| * @q: request_queue being released |
| * |
| * Called from blk_exit_queue(). Responsible for exiting blkcg part. |
| */ |
| void blkcg_exit_queue(struct request_queue *q) |
| { |
| blkg_destroy_all(q); |
| blk_throtl_exit(q); |
| } |
| |
| /* |
| * We cannot support shared io contexts, as we have no mean to support |
| * two tasks with the same ioc in two different groups without major rework |
| * of the main cic data structures. For now we allow a task to change |
| * its cgroup only if it's the only owner of its ioc. |
| */ |
| static int blkcg_can_attach(struct cgroup_taskset *tset) |
| { |
| struct task_struct *task; |
| struct cgroup_subsys_state *dst_css; |
| struct io_context *ioc; |
| int ret = 0; |
| |
| /* task_lock() is needed to avoid races with exit_io_context() */ |
| cgroup_taskset_for_each(task, dst_css, tset) { |
| task_lock(task); |
| ioc = task->io_context; |
| if (ioc && atomic_read(&ioc->nr_tasks) > 1) |
| ret = -EINVAL; |
| task_unlock(task); |
| if (ret) |
| break; |
| } |
| return ret; |
| } |
| |
| static void blkcg_bind(struct cgroup_subsys_state *root_css) |
| { |
| int i; |
| |
| mutex_lock(&blkcg_pol_mutex); |
| |
| for (i = 0; i < BLKCG_MAX_POLS; i++) { |
| struct blkcg_policy *pol = blkcg_policy[i]; |
| struct blkcg *blkcg; |
| |
| if (!pol || !pol->cpd_bind_fn) |
| continue; |
| |
| list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) |
| if (blkcg->cpd[pol->plid]) |
| pol->cpd_bind_fn(blkcg->cpd[pol->plid]); |
| } |
| mutex_unlock(&blkcg_pol_mutex); |
| } |
| |
| static void blkcg_exit(struct task_struct *tsk) |
| { |
| if (tsk->throttle_queue) |
| blk_put_queue(tsk->throttle_queue); |
| tsk->throttle_queue = NULL; |
| } |
| |
| struct cgroup_subsys io_cgrp_subsys = { |
| .css_alloc = blkcg_css_alloc, |
| .css_online = blkcg_css_online, |
| .css_offline = blkcg_css_offline, |
| .css_free = blkcg_css_free, |
| .can_attach = blkcg_can_attach, |
| .css_rstat_flush = blkcg_rstat_flush, |
| .bind = blkcg_bind, |
| .dfl_cftypes = blkcg_files, |
| .legacy_cftypes = blkcg_legacy_files, |
| .legacy_name = "blkio", |
| .exit = blkcg_exit, |
| #ifdef CONFIG_MEMCG |
| /* |
| * This ensures that, if available, memcg is automatically enabled |
| * together on the default hierarchy so that the owner cgroup can |
| * be retrieved from writeback pages. |
| */ |
| .depends_on = 1 << memory_cgrp_id, |
| #endif |
| }; |
| EXPORT_SYMBOL_GPL(io_cgrp_subsys); |
| |
| /** |
| * blkcg_activate_policy - activate a blkcg policy on a request_queue |
| * @q: request_queue of interest |
| * @pol: blkcg policy to activate |
| * |
| * Activate @pol on @q. Requires %GFP_KERNEL context. @q goes through |
| * bypass mode to populate its blkgs with policy_data for @pol. |
| * |
| * Activation happens with @q bypassed, so nobody would be accessing blkgs |
| * from IO path. Update of each blkg is protected by both queue and blkcg |
| * locks so that holding either lock and testing blkcg_policy_enabled() is |
| * always enough for dereferencing policy data. |
| * |
| * The caller is responsible for synchronizing [de]activations and policy |
| * [un]registerations. Returns 0 on success, -errno on failure. |
| */ |
| int blkcg_activate_policy(struct request_queue *q, |
| const struct blkcg_policy *pol) |
| { |
| struct blkg_policy_data *pd_prealloc = NULL; |
| struct blkcg_gq *blkg, *pinned_blkg = NULL; |
| int ret; |
| |
| if (blkcg_policy_enabled(q, pol)) |
| return 0; |
| |
| if (queue_is_mq(q)) |
| blk_mq_freeze_queue(q); |
| retry: |
| spin_lock_irq(&q->queue_lock); |
| |
| /* blkg_list is pushed at the head, reverse walk to allocate parents first */ |
| list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) { |
| struct blkg_policy_data *pd; |
| |
| if (blkg->pd[pol->plid]) |
| continue; |
| |
| /* If prealloc matches, use it; otherwise try GFP_NOWAIT */ |
| if (blkg == pinned_blkg) { |
| pd = pd_prealloc; |
| pd_prealloc = NULL; |
| } else { |
| pd = pol->pd_alloc_fn(GFP_NOWAIT | __GFP_NOWARN, q, |
| blkg->blkcg); |
| } |
| |
| if (!pd) { |
| /* |
| * GFP_NOWAIT failed. Free the existing one and |
| * prealloc for @blkg w/ GFP_KERNEL. |
| */ |
| if (pinned_blkg) |
| blkg_put(pinned_blkg); |
| blkg_get(blkg); |
| pinned_blkg = blkg; |
| |
| spin_unlock_irq(&q->queue_lock); |
| |
| if (pd_prealloc) |
| pol->pd_free_fn(pd_prealloc); |
| pd_prealloc = pol->pd_alloc_fn(GFP_KERNEL, q, |
| blkg->blkcg); |
| if (pd_prealloc) |
| goto retry; |
| else |
| goto enomem; |
| } |
| |
| blkg->pd[pol->plid] = pd; |
| pd->blkg = blkg; |
| pd->plid = pol->plid; |
| } |
| |
| /* all allocated, init in the same order */ |
| if (pol->pd_init_fn) |
| list_for_each_entry_reverse(blkg, &q->blkg_list, q_node) |
| pol->pd_init_fn(blkg->pd[pol->plid]); |
| |
| __set_bit(pol->plid, q->blkcg_pols); |
| ret = 0; |
| |
| spin_unlock_irq(&q->queue_lock); |
| out: |
| if (queue_is_mq(q)) |
| blk_mq_unfreeze_queue(q); |
| if (pinned_blkg) |
| blkg_put(pinned_blkg); |
| if (pd_prealloc) |
| pol->pd_free_fn(pd_prealloc); |
| return ret; |
| |
| enomem: |
| /* alloc failed, nothing's initialized yet, free everything */ |
| spin_lock_irq(&q->queue_lock); |
| list_for_each_entry(blkg, &q->blkg_list, q_node) { |
| if (blkg->pd[pol->plid]) { |
| pol->pd_free_fn(blkg->pd[pol->plid]); |
| blkg->pd[pol->plid] = NULL; |
| } |
| } |
| spin_unlock_irq(&q->queue_lock); |
| ret = -ENOMEM; |
| goto out; |
| } |
| EXPORT_SYMBOL_GPL(blkcg_activate_policy); |
| |
| /** |
| * blkcg_deactivate_policy - deactivate a blkcg policy on a request_queue |
| * @q: request_queue of interest |
| * @pol: blkcg policy to deactivate |
| * |
| * Deactivate @pol on @q. Follows the same synchronization rules as |
| * blkcg_activate_policy(). |
| */ |
| void blkcg_deactivate_policy(struct request_queue *q, |
| const struct blkcg_policy *pol) |
| { |
| struct blkcg_gq *blkg; |
| |
| if (!blkcg_policy_enabled(q, pol)) |
| return; |
| |
| if (queue_is_mq(q)) |
| blk_mq_freeze_queue(q); |
| |
| spin_lock_irq(&q->queue_lock); |
| |
| __clear_bit(pol->plid, q->blkcg_pols); |
| |
| list_for_each_entry(blkg, &q->blkg_list, q_node) { |
| if (blkg->pd[pol->plid]) { |
| if (pol->pd_offline_fn) |
| pol->pd_offline_fn(blkg->pd[pol->plid]); |
| pol->pd_free_fn(blkg->pd[pol->plid]); |
| blkg->pd[pol->plid] = NULL; |
| } |
| } |
| |
| spin_unlock_irq(&q->queue_lock); |
| |
| if (queue_is_mq(q)) |
| blk_mq_unfreeze_queue(q); |
| } |
| EXPORT_SYMBOL_GPL(blkcg_deactivate_policy); |
| |
| /** |
| * blkcg_policy_register - register a blkcg policy |
| * @pol: blkcg policy to register |
| * |
| * Register @pol with blkcg core. Might sleep and @pol may be modified on |
| * successful registration. Returns 0 on success and -errno on failure. |
| */ |
| int blkcg_policy_register(struct blkcg_policy *pol) |
| { |
| struct blkcg *blkcg; |
| int i, ret; |
| |
| mutex_lock(&blkcg_pol_register_mutex); |
| mutex_lock(&blkcg_pol_mutex); |
| |
| /* find an empty slot */ |
| ret = -ENOSPC; |
| for (i = 0; i < BLKCG_MAX_POLS; i++) |
| if (!blkcg_policy[i]) |
| break; |
| if (i >= BLKCG_MAX_POLS) { |
| pr_warn("blkcg_policy_register: BLKCG_MAX_POLS too small\n"); |
| goto err_unlock; |
| } |
| |
| /* Make sure cpd/pd_alloc_fn and cpd/pd_free_fn in pairs */ |
| if ((!pol->cpd_alloc_fn ^ !pol->cpd_free_fn) || |
| (!pol->pd_alloc_fn ^ !pol->pd_free_fn)) |
| goto err_unlock; |
| |
| /* register @pol */ |
| pol->plid = i; |
| blkcg_policy[pol->plid] = pol; |
| |
| /* allocate and install cpd's */ |
| if (pol->cpd_alloc_fn) { |
| list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
| struct blkcg_policy_data *cpd; |
| |
| cpd = pol->cpd_alloc_fn(GFP_KERNEL); |
| if (!cpd) |
| goto err_free_cpds; |
| |
| blkcg->cpd[pol->plid] = cpd; |
| cpd->blkcg = blkcg; |
| cpd->plid = pol->plid; |
| if (pol->cpd_init_fn) |
| pol->cpd_init_fn(cpd); |
| } |
| } |
| |
| mutex_unlock(&blkcg_pol_mutex); |
| |
| /* everything is in place, add intf files for the new policy */ |
| if (pol->dfl_cftypes) |
| WARN_ON(cgroup_add_dfl_cftypes(&io_cgrp_subsys, |
| pol->dfl_cftypes)); |
| if (pol->legacy_cftypes) |
| WARN_ON(cgroup_add_legacy_cftypes(&io_cgrp_subsys, |
| pol->legacy_cftypes)); |
| mutex_unlock(&blkcg_pol_register_mutex); |
| return 0; |
| |
| err_free_cpds: |
| if (pol->cpd_free_fn) { |
| list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
| if (blkcg->cpd[pol->plid]) { |
| pol->cpd_free_fn(blkcg->cpd[pol->plid]); |
| blkcg->cpd[pol->plid] = NULL; |
| } |
| } |
| } |
| blkcg_policy[pol->plid] = NULL; |
| err_unlock: |
| mutex_unlock(&blkcg_pol_mutex); |
| mutex_unlock(&blkcg_pol_register_mutex); |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(blkcg_policy_register); |
| |
| /** |
| * blkcg_policy_unregister - unregister a blkcg policy |
| * @pol: blkcg policy to unregister |
| * |
| * Undo blkcg_policy_register(@pol). Might sleep. |
| */ |
| void blkcg_policy_unregister(struct blkcg_policy *pol) |
| { |
| struct blkcg *blkcg; |
| |
| mutex_lock(&blkcg_pol_register_mutex); |
| |
| if (WARN_ON(blkcg_policy[pol->plid] != pol)) |
| goto out_unlock; |
| |
| /* kill the intf files first */ |
| if (pol->dfl_cftypes) |
| cgroup_rm_cftypes(pol->dfl_cftypes); |
| if (pol->legacy_cftypes) |
| cgroup_rm_cftypes(pol->legacy_cftypes); |
| |
| /* remove cpds and unregister */ |
| mutex_lock(&blkcg_pol_mutex); |
| |
| if (pol->cpd_free_fn) { |
| list_for_each_entry(blkcg, &all_blkcgs, all_blkcgs_node) { |
| if (blkcg->cpd[pol->plid]) { |
| pol->cpd_free_fn(blkcg->cpd[pol->plid]); |
| blkcg->cpd[pol->plid] = NULL; |
| } |
| } |
| } |
| blkcg_policy[pol->plid] = NULL; |
| |
| mutex_unlock(&blkcg_pol_mutex); |
| out_unlock: |
| mutex_unlock(&blkcg_pol_register_mutex); |
| } |
| EXPORT_SYMBOL_GPL(blkcg_policy_unregister); |
| |
| bool __blkcg_punt_bio_submit(struct bio *bio) |
| { |
| struct blkcg_gq *blkg = bio->bi_blkg; |
| |
| /* consume the flag first */ |
| bio->bi_opf &= ~REQ_CGROUP_PUNT; |
| |
| /* never bounce for the root cgroup */ |
| if (!blkg->parent) |
| return false; |
| |
| spin_lock_bh(&blkg->async_bio_lock); |
| bio_list_add(&blkg->async_bios, bio); |
| spin_unlock_bh(&blkg->async_bio_lock); |
| |
| queue_work(blkcg_punt_bio_wq, &blkg->async_bio_work); |
| return true; |
| } |
| |
| /* |
| * Scale the accumulated delay based on how long it has been since we updated |
| * the delay. We only call this when we are adding delay, in case it's been a |
| * while since we added delay, and when we are checking to see if we need to |
| * delay a task, to account for any delays that may have occurred. |
| */ |
| static void blkcg_scale_delay(struct blkcg_gq *blkg, u64 now) |
| { |
| u64 old = atomic64_read(&blkg->delay_start); |
| |
| /* negative use_delay means no scaling, see blkcg_set_delay() */ |
| if (atomic_read(&blkg->use_delay) < 0) |
| return; |
| |
| /* |
| * We only want to scale down every second. The idea here is that we |
| * want to delay people for min(delay_nsec, NSEC_PER_SEC) in a certain |
| * time window. We only want to throttle tasks for recent delay that |
| * has occurred, in 1 second time windows since that's the maximum |
| * things can be throttled. We save the current delay window in |
| * blkg->last_delay so we know what amount is still left to be charged |
| * to the blkg from this point onward. blkg->last_use keeps track of |
| * the use_delay counter. The idea is if we're unthrottling the blkg we |
| * are ok with whatever is happening now, and we can take away more of |
| * the accumulated delay as we've already throttled enough that |
| * everybody is happy with their IO latencies. |
| */ |
| if (time_before64(old + NSEC_PER_SEC, now) && |
| atomic64_cmpxchg(&blkg->delay_start, old, now) == old) { |
| u64 cur = atomic64_read(&blkg->delay_nsec); |
| u64 sub = min_t(u64, blkg->last_delay, now - old); |
| int cur_use = atomic_read(&blkg->use_delay); |
| |
| /* |
| * We've been unthrottled, subtract a larger chunk of our |
| * accumulated delay. |
| */ |
| if (cur_use < blkg->last_use) |
| sub = max_t(u64, sub, blkg->last_delay >> 1); |
| |
| /* |
| * This shouldn't happen, but handle it anyway. Our delay_nsec |
| * should only ever be growing except here where we subtract out |
| * min(last_delay, 1 second), but lord knows bugs happen and I'd |
| * rather not end up with negative numbers. |
| */ |
| if (unlikely(cur < sub)) { |
| atomic64_set(&blkg->delay_nsec, 0); |
| blkg->last_delay = 0; |
| } else { |
| atomic64_sub(sub, &blkg->delay_nsec); |
| blkg->last_delay = cur - sub; |
| } |
| blkg->last_use = cur_use; |
| } |
| } |
| |
| /* |
| * This is called when we want to actually walk up the hierarchy and check to |
| * see if we need to throttle, and then actually throttle if there is some |
| * accumulated delay. This should only be called upon return to user space so |
| * we're not holding some lock that would induce a priority inversion. |
| */ |
| static void blkcg_maybe_throttle_blkg(struct blkcg_gq *blkg, bool use_memdelay) |
| { |
| unsigned long pflags; |
| bool clamp; |
| u64 now = ktime_to_ns(ktime_get()); |
| u64 exp; |
| u64 delay_nsec = 0; |
| int tok; |
| |
| while (blkg->parent) { |
| int use_delay = atomic_read(&blkg->use_delay); |
| |
| if (use_delay) { |
| u64 this_delay; |
| |
| blkcg_scale_delay(blkg, now); |
| this_delay = atomic64_read(&blkg->delay_nsec); |
| if (this_delay > delay_nsec) { |
| delay_nsec = this_delay; |
| clamp = use_delay > 0; |
| } |
| } |
| blkg = blkg->parent; |
| } |
| |
| if (!delay_nsec) |
| return; |
| |
| /* |
| * Let's not sleep for all eternity if we've amassed a huge delay. |
| * Swapping or metadata IO can accumulate 10's of seconds worth of |
| * delay, and we want userspace to be able to do _something_ so cap the |
| * delays at 0.25s. If there's 10's of seconds worth of delay then the |
| * tasks will be delayed for 0.25 second for every syscall. If |
| * blkcg_set_delay() was used as indicated by negative use_delay, the |
| * caller is responsible for regulating the range. |
| */ |
| if (clamp) |
| delay_nsec = min_t(u64, delay_nsec, 250 * NSEC_PER_MSEC); |
| |
| if (use_memdelay) |
| psi_memstall_enter(&pflags); |
| |
| exp = ktime_add_ns(now, delay_nsec); |
| tok = io_schedule_prepare(); |
| do { |
| __set_current_state(TASK_KILLABLE); |
| if (!schedule_hrtimeout(&exp, HRTIMER_MODE_ABS)) |
| break; |
| } while (!fatal_signal_pending(current)); |
| io_schedule_finish(tok); |
| |
| if (use_memdelay) |
| psi_memstall_leave(&pflags); |
| } |
| |
| /** |
| * blkcg_maybe_throttle_current - throttle the current task if it has been marked |
| * |
| * This is only called if we've been marked with set_notify_resume(). Obviously |
| * we can be set_notify_resume() for reasons other than blkcg throttling, so we |
| * check to see if current->throttle_queue is set and if not this doesn't do |
| * anything. This should only ever be called by the resume code, it's not meant |
| * to be called by people willy-nilly as it will actually do the work to |
| * throttle the task if it is setup for throttling. |
| */ |
| void blkcg_maybe_throttle_current(void) |
| { |
| struct request_queue *q = current->throttle_queue; |
| struct cgroup_subsys_state *css; |
| struct blkcg *blkcg; |
| struct blkcg_gq *blkg; |
| bool use_memdelay = current->use_memdelay; |
| |
| if (!q) |
| return; |
| |
| current->throttle_queue = NULL; |
| current->use_memdelay = false; |
| |
| rcu_read_lock(); |
| css = kthread_blkcg(); |
| if (css) |
| blkcg = css_to_blkcg(css); |
| else |
| blkcg = css_to_blkcg(task_css(current, io_cgrp_id)); |
| |
| if (!blkcg) |
| goto out; |
| blkg = blkg_lookup(blkcg, q); |
| if (!blkg) |
| goto out; |
| if (!blkg_tryget(blkg)) |
| goto out; |
| rcu_read_unlock(); |
| |
| blkcg_maybe_throttle_blkg(blkg, use_memdelay); |
| blkg_put(blkg); |
| blk_put_queue(q); |
| return; |
| out: |
| rcu_read_unlock(); |
| blk_put_queue(q); |
| } |
| |
| /** |
| * blkcg_schedule_throttle - this task needs to check for throttling |
| * @q: the request queue IO was submitted on |
| * @use_memdelay: do we charge this to memory delay for PSI |
| * |
| * This is called by the IO controller when we know there's delay accumulated |
| * for the blkg for this task. We do not pass the blkg because there are places |
| * we call this that may not have that information, the swapping code for |
| * instance will only have a request_queue at that point. This set's the |
| * notify_resume for the task to check and see if it requires throttling before |
| * returning to user space. |
| * |
| * We will only schedule once per syscall. You can call this over and over |
| * again and it will only do the check once upon return to user space, and only |
| * throttle once. If the task needs to be throttled again it'll need to be |
| * re-set at the next time we see the task. |
| */ |
| void blkcg_schedule_throttle(struct request_queue *q, bool use_memdelay) |
| { |
| if (unlikely(current->flags & PF_KTHREAD)) |
| return; |
| |
| if (!blk_get_queue(q)) |
| return; |
| |
| if (current->throttle_queue) |
| blk_put_queue(current->throttle_queue); |
| current->throttle_queue = q; |
| if (use_memdelay) |
| current->use_memdelay = use_memdelay; |
| set_notify_resume(current); |
| } |
| |
| /** |
| * blkcg_add_delay - add delay to this blkg |
| * @blkg: blkg of interest |
| * @now: the current time in nanoseconds |
| * @delta: how many nanoseconds of delay to add |
| * |
| * Charge @delta to the blkg's current delay accumulation. This is used to |
| * throttle tasks if an IO controller thinks we need more throttling. |
| */ |
| void blkcg_add_delay(struct blkcg_gq *blkg, u64 now, u64 delta) |
| { |
| if (WARN_ON_ONCE(atomic_read(&blkg->use_delay) < 0)) |
| return; |
| blkcg_scale_delay(blkg, now); |
| atomic64_add(delta, &blkg->delay_nsec); |
| } |
| |
| /** |
| * blkg_tryget_closest - try and get a blkg ref on the closet blkg |
| * @bio: target bio |
| * @css: target css |
| * |
| * As the failure mode here is to walk up the blkg tree, this ensure that the |
| * blkg->parent pointers are always valid. This returns the blkg that it ended |
| * up taking a reference on or %NULL if no reference was taken. |
| */ |
| static inline struct blkcg_gq *blkg_tryget_closest(struct bio *bio, |
| struct cgroup_subsys_state *css) |
| { |
| struct blkcg_gq *blkg, *ret_blkg = NULL; |
| |
| rcu_read_lock(); |
| blkg = blkg_lookup_create(css_to_blkcg(css), bio->bi_disk->queue); |
| while (blkg) { |
| if (blkg_tryget(blkg)) { |
| ret_blkg = blkg; |
| break; |
| } |
| blkg = blkg->parent; |
| } |
| rcu_read_unlock(); |
| |
| return ret_blkg; |
| } |
| |
| /** |
| * bio_associate_blkg_from_css - associate a bio with a specified css |
| * @bio: target bio |
| * @css: target css |
| * |
| * Associate @bio with the blkg found by combining the css's blkg and the |
| * request_queue of the @bio. An association failure is handled by walking up |
| * the blkg tree. Therefore, the blkg associated can be anything between @blkg |
| * and q->root_blkg. This situation only happens when a cgroup is dying and |
| * then the remaining bios will spill to the closest alive blkg. |
| * |
| * A reference will be taken on the blkg and will be released when @bio is |
| * freed. |
| */ |
| void bio_associate_blkg_from_css(struct bio *bio, |
| struct cgroup_subsys_state *css) |
| { |
| if (bio->bi_blkg) |
| blkg_put(bio->bi_blkg); |
| |
| if (css && css->parent) { |
| bio->bi_blkg = blkg_tryget_closest(bio, css); |
| } else { |
| blkg_get(bio->bi_disk->queue->root_blkg); |
| bio->bi_blkg = bio->bi_disk->queue->root_blkg; |
| } |
| } |
| EXPORT_SYMBOL_GPL(bio_associate_blkg_from_css); |
| |
| /** |
| * bio_associate_blkg - associate a bio with a blkg |
| * @bio: target bio |
| * |
| * Associate @bio with the blkg found from the bio's css and request_queue. |
| * If one is not found, bio_lookup_blkg() creates the blkg. If a blkg is |
| * already associated, the css is reused and association redone as the |
| * request_queue may have changed. |
| */ |
| void bio_associate_blkg(struct bio *bio) |
| { |
| struct cgroup_subsys_state *css; |
| |
| rcu_read_lock(); |
| |
| if (bio->bi_blkg) |
| css = &bio_blkcg(bio)->css; |
| else |
| css = blkcg_css(); |
| |
| bio_associate_blkg_from_css(bio, css); |
| |
| rcu_read_unlock(); |
| } |
| EXPORT_SYMBOL_GPL(bio_associate_blkg); |
| |
| /** |
| * bio_clone_blkg_association - clone blkg association from src to dst bio |
| * @dst: destination bio |
| * @src: source bio |
| */ |
| void bio_clone_blkg_association(struct bio *dst, struct bio *src) |
| { |
| if (src->bi_blkg) { |
| if (dst->bi_blkg) |
| blkg_put(dst->bi_blkg); |
| blkg_get(src->bi_blkg); |
| dst->bi_blkg = src->bi_blkg; |
| } |
| } |
| EXPORT_SYMBOL_GPL(bio_clone_blkg_association); |
| |
| static int blk_cgroup_io_type(struct bio *bio) |
| { |
| if (op_is_discard(bio->bi_opf)) |
| return BLKG_IOSTAT_DISCARD; |
| if (op_is_write(bio->bi_opf)) |
| return BLKG_IOSTAT_WRITE; |
| return BLKG_IOSTAT_READ; |
| } |
| |
| void blk_cgroup_bio_start(struct bio *bio) |
| { |
| int rwd = blk_cgroup_io_type(bio), cpu; |
| struct blkg_iostat_set *bis; |
| |
| cpu = get_cpu(); |
| bis = per_cpu_ptr(bio->bi_blkg->iostat_cpu, cpu); |
| u64_stats_update_begin(&bis->sync); |
| |
| /* |
| * If the bio is flagged with BIO_CGROUP_ACCT it means this is a split |
| * bio and we would have already accounted for the size of the bio. |
| */ |
| if (!bio_flagged(bio, BIO_CGROUP_ACCT)) { |
| bio_set_flag(bio, BIO_CGROUP_ACCT); |
| bis->cur.bytes[rwd] += bio->bi_iter.bi_size; |
| } |
| bis->cur.ios[rwd]++; |
| |
| u64_stats_update_end(&bis->sync); |
| if (cgroup_subsys_on_dfl(io_cgrp_subsys)) |
| cgroup_rstat_updated(bio->bi_blkg->blkcg->css.cgroup, cpu); |
| put_cpu(); |
| } |
| |
| static int __init blkcg_init(void) |
| { |
| blkcg_punt_bio_wq = alloc_workqueue("blkcg_punt_bio", |
| WQ_MEM_RECLAIM | WQ_FREEZABLE | |
| WQ_UNBOUND | WQ_SYSFS, 0); |
| if (!blkcg_punt_bio_wq) |
| return -ENOMEM; |
| return 0; |
| } |
| subsys_initcall(blkcg_init); |
| |
| module_param(blkcg_debug_stats, bool, 0644); |
| MODULE_PARM_DESC(blkcg_debug_stats, "True if you want debug stats, false if not"); |